• Title/Summary/Keyword: Wave hindcasting

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Wave Hindcasting on the Storm Waves at the Korean Straits of April, 2016 (2016년 4월 대한해협 폭풍파랑 후측모의 실험)

  • Chun, Hwusub;Ahn, Kyungmo
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.29 no.1
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    • pp.36-45
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    • 2017
  • In the present study, the storm waves at the Korean Straits of April, 2016 have been reproduced by the wave hindcasting, and then their characteristics were investigated. Before the wave hindcasting, the wave measurements at the Korean Straits were analyzed. The analysis showed that the waves at the Korean Straits were dominated by the Northeastern waves, same as those in the East Sea. Accordingly, the wave hindcasting was been carried out with the same condition in Ahn et al. (2016). In the numerical results, the maximum significant wave height at the Korean Straits was 5.06 m, and the corresponding significant wave period was 9.2 s. The computed significant wave heights and wave periods were overestimated by 4 cm and 0.8 s, respectively. After the wave hindcasting, the computed significant wave heights and peak periods were compared with the JONSWAP relationship. This comparison showed that the storm waves at the Korean Straits were close to wind waves, not swell.

Reproduction of Extreme Waves Caused by Typhoon MAEMI with Wave Hindcasting Method, WAM (II) - Characteristics of extreme waves generated by Typhoon MAEMI in the south coast of Korea - (제3세대 파랑추산모형을 이용한 태풍 ‘매미’의 극한파랑 재현 (II) - 태풍 ‘매미’가 야기한 우리나라 남해안 일대의 극한파랑 특성 -)

  • Shin, Seung-Ho;Hong, Key-Yong
    • Journal of Navigation and Port Research
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    • v.28 no.8
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    • pp.745-751
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    • 2004
  • Following a preceding study of Shin et al.(2004), wave fields for a month of September of 2003 are simulated based on the modified WAM cycle 4 model that enables the precise wave hindcasting with fine spatial meshes, and characteristics of extreme waves at the south coast of Korea are analyzed The accuracy of applied wave model is verified by comparing computed wave parameters and corresponding ones measured at Ieodo ocean research station. The wave hindcasting of typhoon 'Maemi' with an hour time interval reveals the extreme wave characteristics at 4 primary locations of south coast of Korea as follows: 1) At the front sea of Chaguido in the south of Jeju-do, the maximum significant wave height, mean wave period and mean wave direction appear to be 7.41m, 13.65s and $6.4^{\circ}$ respectively at 16:00 KST of Sep. 12, 2003. 2) At the entrance of Masan Bay, 12.50m, 13.65s and $1.2^{\circ}$ at 21:00 KST of Sep. 12. 3) At the front sea of Suyoung Bay, 13.85m, 13.81s and $0.2^{\circ}$ at 22;00 KST of Sep. 12. 4) At the front sea of Ulsan port, l1.00m, 13.25s and $2.8^{\circ}$ at 23:00 KST of Sep. 12.

Shallow Water Wave Hindcasting by the Combination of MASCON and SWAN Models (지형을 고려한 해상풍 모델(MASCON)과 SWAN 모델의 결합에 의한 천해파랑 산정)

  • Kim, Ji-Min;Kim, Chang-Hoon;Kim, Do-Sam;Hur, Dong-Soo
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.19 no.1
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    • pp.57-65
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    • 2007
  • Shallow water waves are hindcasted from sea wind fields, which include wave transformations such as shoaling, refraction, diffraction, reflection and wave breaking. In case of estimating sea wind field in shallow water, the sea wind revised from free wind obtained by the typhoon model is widely used. However, this method is not able to consider the effect of land topography on the wind field, which will be important factor for shallow water wave forecasting and hindcasting. In this study, therefore, the effect of land topography on sea wind field in shallow water is investigated for shallow water wave forecasting and hindcasting with high accuracy. The 3-D MASCON model is introduced to consider the influence of land topography on the wind field. And, for two areas divided by the topographical characteristics, i.e. shielded and opened coastal areas, sea wind field is examined by comparison between initial wind field by typhoon model and modified wind field by 3-D MASCON model. Finally, applying these sea wind fields to SWAN model, the results of shallow water wave calculated in shielded and opened coastal areas are compared, and, also, the effect of MASCON model on shallow water wave forecasting and hindcasting is discussed.

Characteristics of Storm Waves at Gangneung port Based on the Wave Hindcasting (파랑 후측 모의 실험 기반 강릉항 폭풍파랑 분석)

  • Ahn, Kyungmo;Hwang, Soon-mi;Chun, Hwusub
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.28 no.6
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    • pp.375-382
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    • 2016
  • In the present study, the wave hindcasting has been performed, and then the characteristics of storm waves at Gangnueng port was investigated, in which the high waves are observed. Comparing the numerical results with the wave measurements at Gangneung port, Niigata, and Hamada, there were good agreements between them. In particular, the Pearson correlation coefficients of significant wave heights and peak periods at Gangneung port were 0.92 and 0.72, respectively. Then the extreme wave analysis on the significant wave heights was carried out for the estimation of the frequency of storm waves. In this analysis, the storm waves over the threshold were fitted to GPD(Generalized Pareto Distribution). According to this analysis, the return period of the storm wave on February, 24, 2008, one of the large storm waves at Gangneung port, was 8.2 months. Among the computed significant wave heights larger than one-year wave, 58.3% of them were resulted from the storm, while the others were from the typhoon. Additionally, the regression analysis on the waves larger than one-month wave has been conducted, and then the relationship between the computed significant wave heights and the significant wave period, $T_{1/3}=7H_s^{0.25}$ was obtained.

Coarse Grid Wave Hindcasting in the Yellow Sea Considering the Effect of Tide and Tidal Current (조석 및 조류 효과를 고려한 황해역 광역 파랑 수치모의 실험)

  • Chun, Hwusub;Ahn, Kyungmo
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.30 no.6
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    • pp.286-297
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    • 2018
  • In the present study, wave measurements at KOGA-W01 were analyzed and then the numerical wind waves simulations have been conducted to investigate the characteristics of wind waves in the Yellow sea. According to the present analysis, even though the location of the wave stations are close to the coastal region, the deep water waves are prevailed due to the short fetch length. Chun and Ahn's (2017a, b) numerical model has been extended to the Yellow Sea in this study. The effects of tide and tidal currents should be included in the model to accommodate the distinctive effect of large tidal range and tidal current in the Yellow Sea. The wave hindcasting results were compared with the wave measurements collected KOGA-W01 and Kyeockpo. The comparison shows the reasonable agreements between wave hindcastings and measured data, however the model significantly underestimate the wave period of swell waves from the south due to the narrow computational domain. Despite the poorly prediction in the significant wave period of swell waves which usually have small wave heights, the estimation of the extreme wave height and corresponding wave period shows good agreement with the measurement data.

Estimation of Design Wave Height for the Waters around the Korean Peninsula

  • Lee, Dong-Young;Jun, Ki-Cheon
    • Ocean Science Journal
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    • v.41 no.4
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    • pp.245-254
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    • 2006
  • Long term wave climate of both extreme wave and operational wave height is essential for planning and designing coastal structures. Since the field wave data for the waters around Korean peninsula is not enough to provide reliable wave statistics, the wave climate information has been generated by means of long-term wave hindcasting using available meteorological data. Basic data base of hindcasted wave parameters such as significant wave height, peak period and direction has been established continuously for the period of 25 years starting from 1979 and for major 106 typhoons for the past 53 years since 1951 for each grid point of the North East Asia Regional Seas with grid size of 18 km. Wind field reanalyzed by European Center for Midrange Weather Forecasts (ECMWF) was used for the simulation of waves for the extra-tropical storms, while wind field calculated by typhoon wind model with typhoon parameters carefully analyzed using most of the available data was used for the simulation of typhoon waves. Design wave heights for the return period of 10, 20, 30, 50 and 100 years for 16 directions at each grid point have been estimated by means of extreme wave analysis using the wave simulation data. As in conventional methodsi of design criteria estimation, it is assumed that the climate is stationary and the statistics and extreme analysis using the long-term hindcasting data are used in the statistical prediction for the future. The method of extreme statistical analysis in handling the extreme vents like typhoon Maemi in 2003 was evaluated for more stable results of design wave height estimation for the return periods of 30-50 years for the cost effective construction of coastal structures.

Reproduction of Extreme Waves Caused by Typhoon MAEMI with Wave Hindcasting Method, WAM (II) - Characteristics of extreme waves generated by Typhoon MAEMI in the south coast of Korea - (제3세대 파랑추산모형을 이용한 태풍 '매미'의 극한파랑 재현 (II) - 태풍 '매미'가 야기한 우리나라 남해안 일대의 극한파랑 특성 -)

  • Shin Seung-Ho;Hong Keyyong
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • 2004.11a
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    • pp.219-225
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    • 2004
  • Following a preceding study if Shin et al.(2004), wave fields for a month if September if 2003 are simulated based on the modified WAM cycle 4 model that enables the precise wave hindcasting with fine spatial meshes, and characteristics of extreme waves at the south roast if Koreo are analyzed The accuracy if applied wave model is verified by comparing computed wave parameters and corresponding ones measured at Ieodo ocean research station. The wave hindasting if typhoon 'Maemi' with an hour time interval reveals the extreme wave characteristics at 4 primary locations if south coast of Korea as follows: 1) At the front sea of Chaguido in the south of Jeju-do, the maximum significant wave height, moon wave period and mean wave direction appear to be 7.41m, 13.65s and $6.4^{\circ}$, respectively at 16:00 KST if Sep. 12, 2003. 2) At the entrance of Masan Bay, 12.50m, 13.65s and $1.2^{\circ}$ at 21:00 KST if Sep. 12. 3) At the front sea of Suyoung Bay, 13.85m, 13.81s and $0.2^{\circ}$ at 22;00 KST if Sep. 12. 4) At the front sea of Ulsan port, 11.00m, 13.25s and $28^{\circ}$ at 23:00 KST if Sep.

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Analysis of Wave Characteristics near Wangdeungdo through Southwest Sea Wave Hindcasting (서남해 파랑 후측모의 실험을 통한 왕등도 인근 파랑 특성 분석)

  • Young Ju Noh;Min Young Sun
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.36 no.2
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    • pp.61-69
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    • 2024
  • Wave conditions are crucial for offshore wind farm design, particularly in determining structural loads and layout. However, there is limited wave hindcasting research for the Wangdeungdo Island area, a potential offshore wind site. This study used the MIKE21 model for a year-long wave hindcast around Wangdeungdo in 2021. Validation showed high reproducibility for significant wave heights with RMSE values of 0.177 and 0.225 and Pearson correlations of 0.971 and 0.970 at Sangwangdeungdo and Buan buoys. Subsequent analysis of the wave characteristics near Wangdeungdo indicated significant seasonal variations and differences in maximum significant wave heights across locations, which are expected to significantly impact the design loads for offshore wind structures.

Reproduction of Extreme Waves Caused by Typhoon MAEMI with Wave Hindcasting Method, WAM (I) - Corrections of directional spreading division and limitation on wave development of WAM model - (제3세대 파랑추산모형을 이용한 태풍매미의 극한파랑 재현 (I) - WAM 모형의 파향격자 분할법 및 파 발달 제한조건의 수정 -)

  • Shin Seung-Ho;Hong Key-yong;Choi Hark-Sun;Hashimoto Noriaki
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • 2004.11a
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    • pp.211-218
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    • 2004
  • The WAM wave model has been widely used for wave hindcasting in the ocean by many domestic and foreign researchers due to its relative simplicity and high accuracy. As this model was originally developed for the condition cf deepwater and comparatively coarse grid size covering wide area, it might produce in a fault result mused by the improper distribution of directional spreading. We extensively investigated involved problems based on WAM Cycle 4 model and suggested the improved WAM model so that it is applicable to both shallow water sea and fine mesh wave simulation. The modified WAM model is verified here by comparing the computed result with and the observed data at Ieodo Ocean Research Station for September of 2003.

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Reproduction of Extreme Waves Caused by Typhoon MAEMI with Wave Hindcasting Method, WAM (I) - Corrections of directional spreading division and limitation on wave development of WAM model - (제3세대 파랑추산모형을 이용한 태풍매미의 극한파랑 재현 (I) - WAM 모형의 파향격자 분할법 및 파 발달 제한조건의 수정-)

  • Shin, Seung-Ho;Hong, Key-Yong;Choi, Hak-Sun;Noriaki Hashimoto
    • Journal of Navigation and Port Research
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    • v.28 no.6
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    • pp.557-564
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    • 2004
  • The WAM wave model has been widely used for wave hindcasting in the ocean by many domestic and foreign researchers due to its relative simplicity and high accuracy. As this model was originally developed for the condition of deepwater and comparatively coarse grid size covering wide area, it might produce in a fault result caused by the improper distribution of directional spreading. We extensively investigated involved problems based on WAM Cycle 4 model and suggested the improved WAM model so that it is applicable to both shallow water sea and fine mesh wave simulation The modified W AM model is verified here by comparing the computed result with and the observed data at Ieodo Ocean Research Station for September of 2003.